Do your homework!
– Choosing a subject that interests you is vital BUT building a blog that enjoys plenty of traffic is going to be an uphill struggle if there aren’t enough people out there that share your interest. That doesn’t mean you have to choose the most popular topics going around either. Far from it. Competition will be far greater for the attention of those topic audiences. Finding the middle ground is the key. Spend time using different search engines to see what’s popular in your area of interest. Google Trends
is an extremely useful tool that allows you to type in keywords and see whether that topic is growing or shrinking over time. It also lets you compare topics to see which appears more popular.